This invention relates to an arrangement for the filtering of a supply air flow, especially for motor vehicles, which contains a filter that is arranged in a housing and can be swivelled out of the supply air flow.
Generally, in arrangements of the above-mentioned type, the filter is swivelled out of the supply air flow when large amounts of air are required for the passenger space. Since the filter must also be swivelled against the supply air flow, the actuating forces are relatively high. In addition, a relatively large space is required to allow the swivelling of the filter out of the supply air flow. Since this space is not available in many motor vehicles, a larger filtering volume that would be possible otherwise cannot be obtained.
Another known arrangement provides for bypassing the filter by means of a bypass pipe which is controlled by a flap. In this arrangement also, a relatively large space is required so that this solution, because of the normally limited space conditions in motor vehicles, can be realized only be sacrificing filtering volume.
An objective of the present invention is to provide an arrangement for filtering a supply air flow that maximizes the filtering volume and can create a free air passage when throughflow of large quantities of air are desired, yet minimizes the space that is required.
This objective is achieved by dividing the filter into two parts rotatably mounted on parallel swivel means for swivelling the two parts away from one another, for the exposing of an air passage means therebetween.
In this arrangement, the two parts need to make only relatively small swivel movements in order to expose a relatively large air passage. The additional space required for the swivelling-out of the two parts is therefore also relatively small so that a large filtering volume is possible. In addition, the actuating forces for the swivelling of the two parts of the filter are smaller because the forces exercised on the filter parts by the supply air flow are lower. During the swivelling-together operation as well as during the swivelling-apart of the filter parts, the supply air flow promotes the swivelling of one of the parts of the filter.
In a preferred embodiment of the present invention, the filter is arranged in a housing in such a way that both parts, in the swivelled-together position, are located in a plane disposed at an angle of approximately 45.degree. with respect to the supply air flow. The rectangular portion of the housing is angled at approximately 45.degree. so that a large filter area is presented to the supply air flow. In the swivelled-apart position, the filter parts are approximately parallel to the direction of the supply air flow. As a result, a large-volume and large-surface filter can be located in a housing that needs to have widened portions only slightly larger than normal to permit the swivelling-away of the filter parts from one another. A preferred embodiment provides that the part of the filter which, in the swivelled-together position, is located closer to the air inlet, be swivelled away in the flow direction of the supply air flow, while the other part of the filter is swivelled away against the flow direction of the supply air flow. The additional space that is required for the swivelling-away is the relatively minor hollow areas of the housing.
In order to fit the two parts of the filter closely together in the closed position, in a preferred embodiment of the invention, a dividing plane extends between the parts of the filter approximately tangentially to arcs described by the swivelling of the parts.
In practice, filters are used that are formed by filter mats arranged behind one another, with the filter mat facing the supply air flow being a submicron particulate air filter, and the filter mat facing away being an activated-carbon filter. In a preferred embodiment of the present invention, the filter contains at least two filter mats arranged behind one another in the flow direction of the supply air flow, which are divided at the dividing plane extending approximately tangentially to the arcs described by the swivelling of the filter parts. In order to allow a wide tolerance for the dividing planes while avoiding throughflow of unfiltered air when the filter is closed, in a preferred embodiment the dividing planes between the identical filter mats are staggered with respect to one another. Also, a third dividing plane is provided that extends between and perpendicular to the two tangential dividing planes.
In a preferred embodiment of the invention, a combined adjusting drive for the two parts of the filter is provided and is arranged outside the housing. This adjusting drive can be relatively small because during both the swivelling-together and the swivelling-apart operations, only one part of the filter must swivel against the flow direction of the supply air flow.